Insulin is a hormone needed by the body to absorb glucose from the blood into fat, liver, and skeletal muscle cells, among others. Patients with diabetes either do not produce insulin (type 1 diabetes) or produce insulin but are resistant to insulin's effects (type 2 diabetes) and so their bodies cannot break down the sugars and starches from food into glucose for use as energy by the body. Patients with type 1 and type 2 diabetes can treat their condition in multiple ways including dietary changes, exercise, non-insulin based medications, or insulin. The non-insulin medication may come in the form of an oral agent, for example, and the insulin may be delivered in multiple ways including syringes, pre-filled insulin pens, or an insulin pump. Some patients may be prescribed treatment regimes that employ several treatments for their complementary effects. For example, a patient may receive a non-insulin based medication in addition to insulin when the non-insulin based medication is designed to improve the patient's responsiveness to insulin. Examples of non-insulin medications include forms of biguanides, sulfonylureas, megalitindes, d-phenylalanine derivatives, thiazolidinediones, pioglitazones, DDP-4 inhibitors, alpha-glucosidase inhibitors, and bile acid sequestrants. Another patient may instead receive a different combination of rapid-acting, short-acting, intermediate-acting, long-acting, and pre-mixed insulin, depending on the patient's symptoms, and based on the patient's insulin sensitivity. Examples of possible delivery methods of these different types of insulin include syringes, insulin pens, insulin pumps, jet injectors, inhaled insulin, and the like. Based on the understanding of a patient's physiology, different combinations of these different treatments are prescribed by medical professionals to manage a patient's diabetes.
Insulin sensitivity (SI) is an index that describes the effectiveness of a patient's insulin reaction to glucose. In the late 1970s, a hyperinsulinemic-euglycemic clamp technique was proposed for measuring the whole-body SI in the hospital setting. Two alternatives to the hyperinsulinemic-euglycemic clamp technique were intravenous glucose tolerance tests (VGTT) and oral glucose tolerance tests (OGTT). In VGTT and OGTT, a predetermined amount of glucose is intravenously or orally dosed and the results measured. An oral minimal model is a useful tool for insulin sensitivity estimation based on OGTT data. Although these traditional techniques are effective and robust, the patient must be in an inpatient clinical setting either with intravenous lines attached or the patient must endure multiple venipunctures. These procedures are invasive to the patient, disrupt the patients' daily insulin treatment in the home or other setting, and only provide a one data point as to the patient's condition. Accordingly, the above described treatment regimes for diabetic patients did not consider the possibility that a patient's insulin sensitivity could vary over time.
Recently, improvements in medical technology have allowed for more comprehensive glucose monitoring of the patient through the use of wearable glucose monitors, for example. In addition, insulin pumps have been miniaturized so that patients can easily adjust the insulin dose as needed, and insulin pens have begun including wireless technologies to report various types of information. The advent of these glucose monitors and insulin delivery systems have improved patients' ability to understand their condition and to conveniently manage their own treatment, within the boundaries set by their medical professionals.
Although others, including those mentioned below in the Background References section, have proposed estimating a patient's insulin sensitivity using pump data and continuous glucose monitoring data, those who have previously estimated insulin sensitivity assumed that insulin sensitivity was a time invariant physiological parameter at least during the testing process. Studies have, however, shown that insulin sensitivity does vary significant in response to a variety of factors including circadian rhythm, physical activity, dietary habits, and illness or stress. Dynamic insulin sensitivity indexes were therefore devised to address this improved understanding, and it has been demonstrated that stochastic modeling can provide first order estimates of insulin sensitivity. The application of the improved understanding of the dynamic nature of a patient's insulin sensitivity has not, however, been incorporated into a patient's treatment regime.
The techniques described here consider insulin sensitivity to be a time-varying physiological parameter and utilizes continuous glucose monitoring and insulin delivery data to quantify insulin sensitivity of the patient over time. Further, insulin sensitivity can be used for tracking the state of the patient's condition and adjust the treatment plans so that the appropriate treatment regime is applied to a patient.